package day13.problem3;

//重排字符串
//https://ac.nowcoder.com/acm/problem/222104

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        String s = in.next();
        int[] hash = new int[26];
        int maxCount = 0;
        char mCh = ' ';
        for(char ch : s.toCharArray()) {
            if(++hash[ch-'a'] > maxCount) {
                mCh = ch;
                maxCount = hash[ch-'a'];
            }
        }
        if(maxCount > (n+1)/2) {
            System.out.println("no");
            return;
        }
        char[] arr = new char[n];
        int i = 0;
        for(; i<n && hash[mCh-'a'] > 0; i+=2) {
            arr[i] = mCh;
            hash[mCh-'a']--;
        }
        if(i >= n) i = 1;
        for(int j = 0; j<26; j++) {
            while(hash[j]-- > 0) {
//                 System.out.println(i);
                arr[i] = (char)(j + 'a');
                i += 2;
                if(i >= n) i = 1;
            }
        }
        System.out.println("yes");
        System.out.println(new String(arr));
    }
}